In vitro activity of imipenem/relebactam against Pseudomonas aeruginosa isolates recovered from ICU patients in Spain and Portugal (SUPERIOR and STEP studies)

OBJECTIVES

To study the in vitro activity of imipenem/relebactam and comparators and the imipenem/relebactam resistance mechanisms in a Pseudomonas aeruginosa collection from Portugal (STEP, 2017-18) and Spain (SUPERIOR, 2016-17) surveillance studies.

METHODS

P. aeruginosa isolates (n = 474) were prospectively recovered from complicated urinary tract (cUTI), complicated intra-abdominal (cIAI) and lower respiratory tract (LRTI) infections in 11 Portuguese and 8 Spanish ICUs. MICs were determined (ISO broth microdilution). All imipenem/relebactam-resistant P. aeruginosa isolates (n = 30) and a subset of imipenem/relebactam-susceptible strains (n = 32) were characterized by WGS.

RESULTS

Imipenem/relebactam (93.7% susceptible), ceftazidime/avibactam (93.5% susceptible) and ceftolozane/tazobactam (93.2% susceptible) displayed comparable activity. The imipenem/relebactam resistance rate was 6.3% (Portugal 5.8%; Spain 8.9%). Relebactam restored imipenem susceptibility to 76.9% (103/134) of imipenem-resistant isolates, including MDR (82.1%; 32/39), XDR (68.8%; 53/77) and difficult-to-treat (DTR) isolates (67.2%; 45/67). Among sequenced strains, differences in population structure were detected depending on the country: clonal complex (CC)175 and CC309 in Spain and CC235, CC244, CC348 and CC253 in Portugal. Different carbapenemase gene distributions were also found: VIM-20 (n = 3), VIM-1 (n = 2), VIM-2 (n = 1) and VIM-36 (n = 1) in Spain and GES-13 (n = 13), VIM-2 (n = 3) and KPC-3 (n = 2) in Portugal. GES-13-CC235 (n = 13) and VIM type-CC175 (n = 5) associations were predominant in Portugal and Spain, respectively. Imipenem/relebactam showed activity against KPC-3 strains (2/2), but was inactive against all GES-13 producers and most of the VIM producers (8/10). Mutations in genes affecting porin inactivation, efflux pump overexpression and LPS modification might also be involved in imipenem/relebactam resistance.

CONCLUSIONS

Microbiological results reinforce imipenem/relebactam as a potential option to treat cUTI, cIAI and LRTI caused by MDR/XDR P. aeruginosa isolates, except for GES-13 and VIM producers.

Epidemiology of Clostridioides difficile Infection in Portugal: A Retrospective, Observational Study of Hospitalized Patients

INTRODUCTION

Clostridioides difficile is the main cause of healthcare-associated diarrhea in Europe and North America. The aim of this study was to characterize the epidemiology and clinical burden of Clostridioides difficile infection among hospitalized patients in Portugal.

MATERIAL AND METHODS

Retrospective study conducted in six public hospital centers in Portugal. All primary Clostridioides difficile infection episodes and related recurrences occurring in 2017, as well as episodes developing two to eight weeks after the last episode diagnosed in that year, were documented. The National Reference Laboratory (National Institute of Health Dr. Ricardo Jorge) provided national surveillance data on Clostridioides difficile infection.

RESULTS

A total of 385 inpatients with at least one primary episode diagnosed in 2017 were included. Most patients were aged over 70 years-old (73.2%). The included patients developed 451 episodes during the observation period. Approximately 44% of primary episodes were community-associated. Most episodes (94.9%) occurred in patients with one or more risk factors, with recent antibiotic exposure being particularly common (86.0%). All-cause in-hospital mortality was 19.5%, being significantly higher in patients aged over 65 years-old versus those aged 18 to 64 years-old (22.4% vs 7.8%, respectively). Over 50 different ribotypes were observed among 206 Clostridioides difficile strains received by the National Reference Laboratory.

CONCLUSION

In Portugal, hospitalized patients with Clostridioides difficile infection are mostly older patients presenting risk factors for the development of this infection, particularly recent antibiotic exposure. Mortality is disproportionately high among the older population. Community-associated Clostridioides difficile infection is common among inpatients with this infection.

Distinct epidemiology and resistance mechanisms affecting ceftolozane/tazobactam in Pseudomonas aeruginosa isolates recovered from ICU patients in Spain and Portugal depicted by WGS

Objectives

To analyse the epidemiology, the resistome and the virulome of ceftolozane/tazobactam-susceptible or -resistant Pseudomonas aeruginosa clinical isolates recovered from surveillance studies in Portugal (STEP, 2017–18) and Spain (SUPERIOR, 2016–17).

Methods

P. aeruginosa isolates were recovered from intra-abdominal, urinary tract and lower respiratory tract infections in ICU patients admitted to 11 Portuguese and 8 Spanish hospitals. MICs were determined (ISO-standard broth microdilution, EUCAST 2020 breakpoints). A subset of 28 ceftolozane/tazobactam-resistant P. aeruginosa isolates were analysed and compared with 28 ceftolozane/tazobactam-susceptible P. aeruginosa strains by WGS.

Results

Clonal complex (CC) 235 (27%) and CC175 (18%) were the most frequent, followed by CC244 (13%), CC348 (9%), CC253 (5%) and CC309 (5%). Inter-hospital clonal dissemination was observed, limited to a geographical region (CC235, CC244, CC348 and CC253 in Portugal and CC175 and CC309 in Spain). Carbapenemases were detected in 25 isolates (45%): GES-13 (13/25); VIM type (10/25) [VIM-2 (4/10), VIM-20 (3/10), VIM-1 (2/10) and VIM-36 (1/10)]; and KPC-3 (2/25). GES-13-CC235 (13/15) and VIM type-CC175 (5/10) associations were observed. Interestingly, KPC-3 and VIM-36 producers showed ceftolozane/tazobactam-susceptible phenotypes. However, ceftolozane/tazobactam resistance was significantly associated with GES-13 and VIM-type carbapenemase production. Six non-carbapenemase producers also displayed ceftolozane/tazobactam resistance, three of them showing known ceftolozane/tazobactam resistance-associated mutations in the PBP3 gene, ftsI (R504C and F533L). Overall, an extensive virulome was identified in all P. aeruginosa isolates, particularly in carbapenemase-producing strains.

Conclusions

GES-13-CC235 and VIM type-CC175 were the most frequent MDR/XDR P. aeruginosa clones causing infections in Portuguese and Spanish ICU patients, respectively. Ceftolozane/tazobactam resistance was mainly due to carbapenemase production, although mutations in PBP-encoding genes may additionally be involved.

Longitudinal analysis of the in vitro activity of ceftazidime/avibactam versus Enterobacteriaceae, 2012-2016

OBJECTIVES

The in vitro activities of ceftazidime/avibactam and comparator antimicrobial agents were analysed against 59 828 Enterobacteriaceae isolates collected by 190 centres from all global regions except North America from 2012-2016 as part of the International Network for Optimal Resistance Monitoring (INFORM) global surveillance programme.

METHODS

Antimicrobial susceptibility testing was performed using Clinical and Laboratory Standards Institute broth microdilution panels at a central reference laboratory, except for isolates collected in China that were tested using frozen, dehydrated broth microdilution panels at a central laboratory in China. The presence of extended-spectrum β-lactamases (ESBLs) was confirmed by multiplex PCR assays.

RESULTS

Ceftazidime/avibactam was the most active agent against all Enterobacteriaceae (MIC₉₀, ≤1mg/L, ≥98.4% susceptibility). High rates of susceptibility (>88%) were observed amongst Citrobacter freundii, Citrobacter spp., Enterobacter spp., Escherichia coli, Klebsiella pneumoniae and Klebsiella oxytoca to colistin, meropenem, amikacin and tigecycline. Ceftazidime/avibactam showed consistent in vitro activity against ESBL-positive isolates of E. coli (n=5674; MIC₉₀, 0.5mg/L, 99.5% susceptible), K. pneumoniae (n=7097; MIC₉₀, 2mg/L, 97.0% susceptible) and K. oxytoca (n = 565; MIC₉₀, 1mg/L, 96.8% susceptible). Isolates identified as metallo-β-lactamase-positive (n=242) were not susceptible to ceftazidime/avibactam but were susceptible to tigecycline (76.9%) and colistin (n=194 isolates tested; 92.8%).

CONCLUSIONS

Clinical Enterobacteriaceae isolates, including ESBL-positive phenotypes, collected globally (excluding North America) from 2012-2016 were highly susceptible to ceftazidime/avibactam, suggesting it is a useful agent for serious infections caused by multidrug-resistant organisms belonging to the family Enterobacteriaceae when therapeutic options are limited.

mcr-1 and blaKPC-3 in Escherichia coli Sequence Type 744 after Meropenem and Colistin Therapy, Portugal

Escherichia coli Ec36 was recovered from a patient in Portugal after treatment with meropenem and colistin. Besides an IncF plasmid with Tn1441d-bla_KPC-3, already reported in clinical strains in this country, E. coli Ec36 co-harbored an IncX4::mcr-1 gene. Results highlight emerging co-resistance to carbapenems and polymyxins after therapy with drugs from both classes.

Evaluation of vancomycin MIC creep in Staphylococcus aureus

OBJECTIVES

Vancomycin is the primary treatment for methicillin-resistant Staphylococcus aureus (MRSA). However, an increasing proportion of MRSA isolates with high minimum inhibitory concentrations (MICs) within the susceptible range (vancomycin 'MIC creep') is being observed. The aim of this study was to assess the vancomycin MIC distribution for S. aureus isolates over a period of 4 years in Centro Hospitalar Baixo Vouga (Aveiro, Portugal) and to identify differences in vancomycin MIC determined by different susceptibility testing methods.

METHODS

For each S. aureus isolate, the vancomycin MIC was assayed by the VITEK^®2 automated system and the broth microdilution testing method.

RESULTS

The results showed significant differences in vancomycin MIC by different methods (P=0.021, sign test) and did not suggest the presence of vancomycin MIC creep during the study period.

CONCLUSIONS

Vancomycin MIC creep is a regional problem, therefore it can only be assessed through the evaluation of local susceptibility profiles, and antibiogram based on real MIC assay should be an essential element in local MRSA infection clinical management.

Proteomic profile of susceptible and multidrug-resistant clinical isolates of Escherichia coli and Klebsiella pneumoniae using label-free and immunoproteomic strategies

Infectious diseases caused by multidrug-resistant (MDR) Enterobacteriaceae have exponentially increased in the past decade, and are a major concern in hospitals. In the first part of the work, we compared the proteome profile of MDR and susceptible clinical isolates of Escherichia coli and Klebsiella pneumoniae in order to identify possible biological processes associated with drug resistance and susceptible phenotypes, using a label-free approach. In the second part, we used an immunoproteomics approach to identify immunoreactive proteins in the same isolates. A total of 388 and 377 proteins were identified in MDR and susceptible E. coli, respectively, evidencing that biological processes related to translation are upregulated in E. coli MDR, while there is an upregulation of processes related to catalytic activity in K. pneumoniae MDR. Both MDR strains show downregulation of processes related to amino acid activation and tRNA amino-acylation. Our data also suggest that MDR strains have higher immunoreactivity than the susceptible strains. The application of high-throughput mass spectrometry (MS) and bioinformatics to the study of modulation of biological processes might shed light on the characterization of multidrug resistance in bacteria.

Genetically unrelated multidrug- and carbapenem-resistant Citrobacter freundii detected in outpatients admitted to a Portuguese hospital

OBJECTIVES

Non-clonal, carbapenem- and multidrug-resistant Citrobacter freundii isolates were collected from unrelated outpatients admitted to a Portuguese hospital emergency department. One patient lived in a nursing home and was never hospitalised, whereas the other patient was repeatedly hospitalised in this hospital. The aim of this study was to unveil the molecular mechanisms associated with the carbapenem resistance of these isolates and to assess its potential dissemination.

METHODS

Isolate identification was performed by VITEK^®2 and was confirmed by 16S rDNA sequencing. The clonal relationship of the isolates was evaluated by repetitive element palindromic PCR (rep-PCR). Antibiotic susceptibility was determined using the automatic VITEK^®2 AES system and disk diffusion assay. β-Lactamases, porins and mobile genetic elements were characterised by PCR and sequencing. Pulsed-field gel electrophoresis (PFGE) and Southern blot hybridisation were used to determine the genetic location of integrons, and their transferability was tested by conjugation.

RESULTS

No genetic relatedness was found, suggesting different origins of the isolates. In isolate Cf254 a VIM-2 carbapenemase integrated in In58 was detected, located in a high-frequency conjugative IncL/M plasmid that also carried CTX-M-15 and CMY-39 genes. VIM-1 in isolate Cf872 was chromosomal. This is the first description in Portugal of VIM carbapenemases in C. freundii. Loss/alteration of porins was also detected.

CONCLUSIONS

Emergence of carbapenem-resistant Enterobacteria is not confined to the nosocomial environment. Community-acquired strains appear to be in circulation between inpatients and outpatients, spreading carbapenem resistance genes by horizontal gene transfer.

Physicians' attitudes and knowledge concerning antibiotic prescription and resistance: questionnaire development and reliability

BACKGROUND

Understanding physicians' antibiotic-prescribing behaviour is fundamental when it comes to improving antibiotic use and tackling the growing rates of antimicrobial resistance. The aim of the study was to develop and validate--in terms of face validity, content validity and reliability--an instrument designed to assess the attitudes and knowledge underlying physician antibiotic prescribing.

METHODS

The questionnaire development and validation process comprised two different steps, namely: (1) content and face validation, which included a literature review and validation both by physicians and by Portuguese language and clinical psychology experts; and (2) reliability analysis, using the test-retest method, to assess the questionnaire's internal consistency (Cronbach's alpha) and reproducibility (intraclass correlation coefficient--ICC). The questionnaire includes 17 items assessing attitudes and knowledge about antibiotic prescribing and resistances and 9 items evaluating the importance of different sources of knowledge. The study was conducted in the catchment area covered by Portugal's Northern Regional Health Administration and used a convenience sample of 61 primary-care and 50 hospital-care physicians.

RESULTS

Response rate was 64% (49% to retest) for primary-care physicians and 66% (60% to retest) for hospital-care physicians. Content validity resulted in 9 changes to professional concepts. Face validity assessment resulted in 19 changes to linguistic and interpretative terms. In the case of the reliability analysis, the ICC values indicated a minimum of fair to good reproducibility (ICC > 0.4), and the Cronbach alpha values were satisfactory (α > 0.70).

CONCLUSIONS

The questionnaire developed is valid--in terms of face validity, content validity and reliability--for assessing physicians' attitudes to and knowledge of antibiotic prescribing and resistance, in both hospital and primary-care settings, and could be a very useful tool for characterising physicians' antibiotic-prescribing behaviour.

Methicillin-resistant Staphylococcus aureus carrying the new mecC gene--a meta-analysis

In 2011, a new mecA gene homolog, named mecC gene, was found in isolates from both humans and animals. The discovery of methicillin-resistant Staphylococcus aureus (MRSA) carrying the mecC gene has caused speculations about the origin, epidemiology, and impact of these isolates. The objective of this work is to perform a meta-analysis on the prevalence of mecC MRSA, based on previously published results. Meta-analysis showed that the overall pooled prevalence is 0.009% (95% confidence interval=0.05-0.013) and that there was evidence of heterogeneity (P<0.01, I(2)=97%). In conclusion, the very low reported prevalence provides an important baseline to monitor the epidemiology of this emerging form of MRSA.

Characterization of the toxicological effects of aminocarb on rats: hematological, biochemical, and histological analyses

Aminocarb is a widely applied carbamate insecticide with action of controlling pests such as Lepidoptera and Coleoptera. In this study, subchronic effects on Wistar rats were investigated using hematological, biochemical, and histological techniques. Rats were exposed orally at sublethal levels of 10, 20, or 40 mg/kg body weight (groups A, B, and C, respectively) for 14 d. Hematological results revealed no statistical differences after 1 d of exposure but significant reduction in white blood cells detected after 7 d of exposure in group C, as well as, in all treated groups after 14 d of exposure. Biochemical data showed a decrease of acetylcholinesterase activity in all groups after 1 d of exposure with a return to normal after 7 and 14 d. Significant increase in alkaline phosphatase activity of rats exposed to aminocarb was noted after 7 d of treatment. The levels of triglycerides were also significantly decreased. The present investigation also showed a significant increase in content of serum urea and creatinine in animals from group A (14 d), and from groups B and C (7 and 14 d). Histological results demonstrated hemorrhagic focus on hepatic and renal parenchyma in all exposed groups. Taken together, the attained results were dose dependent and indicated adverse effects of aminocarb on hepatic and renal functions, as well as on immune responsiveness at sublethal tested doses.

Subacute effects of the thiodicarb pesticide on target organs of male Wistar rats: biochemical, histological, and flow cytometry studies

Thiodicarb, a carbamate pesticide widely used on crops, may pose several environmental and health concerns. This study aimed to explore its toxicological profile on male rats using hematological, biochemical, histopathological, and flow cytometry markers. Exposed animals were dosed daily at 10, 20, or 40 mg/kg/body weight (group A, B, and C, respectively) during 30 d. No significant changes were observed in hematological parameters among all groups. After 10 d, a decrease of total cholesterol levels was noted in rats exposed to 40 mg/kg. Aspartate aminotransferase (AST) activity increased (group A at 20 d; groups A and B at 30 d) and alkaline phosphatase (ALP) (group B at 30 d) activity significantly reduced. At 30 d a decrease of some of the other evaluated parameters was observed with total cholesterol and urea levels in group A as well as total protein and creatinine levels in groups A and B. Histological results demonstrated multi-organ dose-related damage in thiodicarb-exposed animals, evidenced as hemorrhagic and diffuse vacuolation in hepatic tissue; renal histology showed disorganized glomeruli and tubular cell degeneration; spleen was ruptured with white pulp and clusters of iron deposits within red pulp; significant cellular loss was noted at the cortex of thymus; and degenerative changes were observed within testis. The histopathologic alterations were most prominent in the high-dose group. Concerning flow cytometry studies, an increase of lymphocyte number, especially T lymphocytes, was seen in blood samples from animals exposed to the highest dose. Taken together, these results indicate marked systemic organ toxicity in rats after subacute exposure to thiodicarb.

Carriage of qnrA1 and qnrB2, blaCTX-M15, and complex class 1 integron in a clinical multiresistant Citrobacter freundii isolate

A multiresistant Citrobacter freundii strain was recovered from a catheter from a patient hospitalized in Aveiro, Portugal. This strain harbored quinolone resistance genes, qnrA1 and qnrB2, both in a large plasmid.

First description of Klebsiella pneumoniae clinical isolates carrying both qnrA and qnrB genes in Portugal

In the present study, 21 multidrug-resistant Klebsiella pneumoniae isolates were recovered from patients hospitalised in the Intensive Care Unit of Hospital Infante D. Pedro in Aveiro, Portugal. Fifteen isolates carried qnr genes. Four strains harboured the quinolone resistance genes qnrA and qnrB, both located on a large plasmid in two strains (KP4 and KP10) and on different plasmids in two strains (KP5 and KP6). These findings indicate an extremely high prevalence of qnr genes associated with various mobile elements such as ISCR1 and class 1 integrons.

[Streptococcal pharyngitis: clinical suspicion versus diagnosis]

INTRODUCTION

Pharyngitis is a very prevalent illness in the ambulatory care setting. Its diagnosis is a challenge, especially in the differentiation between the viric and streptococcal causes.

MATERIALS AND METHODS

A formulary was made to register the clinical and laboratory data; a throat swab for culture was obtained from all the children who presented to the emergency department with sore throat and/or signs of pharyngitis/tonsillitis, for a period of three months (15th of April to 15th of July of 2006). The signs and symptoms, prescribed antibiotherapy and frequency of false diagnostics were evaluated and the clinical suspicion compared with the diagnosis by culture.

RESULTS

158 children were evaluated, with a median age of four years, with a male predominance (56%). The period that showed the greatest number of cases was the first fifteen days of May. Forty-three percent of the cultures were positive for Streptococcus pyogenes. The more frequent signs and symptoms in pharyngitis were pharyngeal erythema (98%), fever (86%) and sore throat (78%). A significative statistical difference was found for cough, scarlatiniform rash, tonsillar exudate, palatal petechiae and tonsillar swelling. Of the signs and symptoms studied, only three of them presented a positive predictive value superior to 50%: scarlatiniform rash (85%), palatal petechiae (63%) and cough (57%). The presence of tonsillar exudate had a positive predictive value for non-streptococcal pharyngitis of 70%. Fifty-three percent of the doctors considered streptococcal pharyngitis highly probable, and from this, 56% had a positive culture for Streptococcus. Those who considered a low probability, the culture was positive in 28%. There were 37% of false diagnosis.

DISCUSSION

The distinction between streptococcal pharyngitis and non-streptococcal pharyngitis is not always correct when based on clinical characteristics. The use of diagnostic tests is important in order to avoid unnecessary antibiotherapy as well as to allow the correct use in the positive cases.

[Monitoring antibiotic consumption in the surgery and orthopaedics]

Monitoring antibiotic consumption is a valuable tool which has been increasingly used in the last years due to the current concern with the emergence of resistant microbial strains. The present study aimed at monitoring antibiotic consumption, evaluating the economic impact of hospital antibiotic prescription and assessing the relationship between the prescribed antibiotics and the indications for either prophylactic or therapeutic use. This was a longitudinal pilot-study for which data were collected in six privately managed public hospital units during the month of May 2004, with a resulting sample of 1,122 admitted patients. We observed a prescription incidence rate of 76.9%, corresponding to a total of 1,154 dispensed antimicrobials, with a mean 71.2% of these antimicrobials being dispensed for the prophylaxis of surgical site infection (SSI). The mean cost of antibiotic courses was higher in cases of "suspected infection" (9.09 euro) or "confirmed infection" (8.74 euro) and lower in cases of "prophylaxis" (5.67 euro), a finding which is explained by the shorter mean duration of the later. There was a considerable variation among the different hospital units regarding the type of antibiotic compound that was used for SSI prophylaxis, with a mean duration of antibiotic use of 2.61 days for this indication and about half of the prophylactic regimens lasting longer than 24 hours, a fact that suggests an insufficient observation of the current recommendations for antibiotic use in SSI prophylaxis. This finding indicates the need for an investigation on the actual existence of local recommendations for SSI prophylaxis in individual hospital units and also for the evaluation of the compliance of practicing surgeons with eventually existing recommendations.